Metal-directed self-assembly has been applied to prepare supramolecular coordination polygons which adopt tetrahedral () or trigonal disklike topologies (). In the solid state, assembles into a stable halide-metal-organic material (), which catalyzes HO oxidation under photo- and electrocatalytic conditions, operating with a maximum TON = 78 and TOF = 1.26 s.
View Article and Find Full Text PDFPolyoxometalates (POMs) are commonly prepared using a "bottom-up" synthetic procedure. The alternative "top-down" approach of disassembling a pre-formed POM unit to generate new synthetic intermediates is promising, but relatively comparatively underused. In this paper, a rationale for the top-down method is provided, demonstrating that this approach can generate compounds that are fundamentally inaccessible from simple bottom-up assembly.
View Article and Find Full Text PDFA dual-porous, three-dimensional, metal-organic framework [ZnO(2,6-NDC)(BTB)] (MOF-205, BET = 4200 m/g) has been synthesized using microwave power as an alternative energy source for the first time, and its catalytic activity has been exploited for CO-epoxide coupling reactions to produce five-membered cyclic carbonates under solvent-free conditions. Microwave synthesis was performed at different time intervals to reveal the formation of the crystals. Significant conversion of various epoxides was obtained at room temperature, with excellent selectivity toward the desired five-membered cyclic carbonates.
View Article and Find Full Text PDFA water stable zinc-MOF (ZnGlu) catalyst was facilely prepared from the proteinogenic amino acid, l-glutamic acid at room temperature in aqueous medium. CO2 fixations were promoted by the ZnGlu catalyst's inherently coordinated water and externally added water in yielding cyclic carbonate and cyclic urethane at room temperature. This eliminates the need for catalyst activation, making ZnGlu a ready-to-use catalyst.
View Article and Find Full Text PDFReported is the application of ZIF-90, which is a highly porous zeolitic imidazolate framework, as a novel catalyst for the cycloaddition of propylene oxide (PO) with CO in the absence of co-catalysts and solvents under moderate reaction conditions. The effects of various reaction parameters were investigated. The activity of ZIF-90 was compared with that of various metal-organic-framework (MOF)-based catalysts for the cycloaddition of PO with CO .
View Article and Find Full Text PDFA novel application of alkanolamines, widely employed as CO2 scrubbers in catalyzing the insertion of CO2 into epoxides generating cyclic carbonates in excellent yield and selectivity via the synergistic activity of hydroxyl and amine groups, is unravelled along with computational studies.
View Article and Find Full Text PDFNaturally occurring amino acids were identified as efficient co-catalysts for the alkali metal halide-mediated synthesis of cyclic carbonates from carbon dioxide and epoxides under mild, solvent free reaction conditions. The binary system of histidine/potassium iodide gave an appreciable turnover number of 535 for propylene oxide in 3 h. Detailed studies evaluating a variety of amino acids revealed that the basic amino acids afforded better conversion rates.
View Article and Find Full Text PDFA mixed-linker nanoporous coordination polymer Zn2(HIP)2(bipy)(H2O)2 x H2O (ZnHipBipy) constructed from polyfunctional linker 5-hydroxy isophthalic acid (HIP) and exo-bidentate ligand 4,4'-bipyridyl (bipy) was employed as heterogeneous catalyst for allyl glycidyl carbonate (AGC) synthesis from CO2 and allyl glycidyl ether (AGE) under solventless conditions. Besides being the organic linker, 5-hydroxy isophthalic acid enriches the functionality of the material through accessible hydroxyl group capable of contributing extensive hydrogen bonding interactions. The cycloaddition of CO2 and epoxide was catalyzed through a synergistic pathway offered by inherent hydroxyl group together with the catalytically active metal centre.
View Article and Find Full Text PDFMicrowave-assisted quaternization of glycine (GLY) resulted in the synthesis of an efficient catalyst, quaternized glycine (QGLY), for the solventless synthesis of cyclic carbonates from epoxides and CO2 under mild reaction conditions. Density functional theory was used to simulate the synergistic influence of the COOH group and the halide ion of QGLY in enhancing the catalytic activity.
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